Diagnostic cough-monitoring techniques

ABSTRACT

The rate at which a human subject coughs may be determined by providing a microphone, a transmitter connected to the microphone, a receiver, a counter, and a conditioning circuit that enables the counter to advance in response to a cough sound.

United States Patent [72] Inventors Leonard C. Gunn Chicago, 1.; Donald A. Burns, Kenosha, Wis. [21 1 Appl. No. 839,309 [22] Filed July 7,1969 [45] Patented July 20, I971 [73] Assignee Abbott Laboratories [54] DIAGNOSTIC COUCH-MONITORING Barr, N. L., THE MILITARY SURGEON, Feb. 1954, V01. 114, No. 2 pp. 79-83, (copy in GR. 335, CL. 128/21) Geddes, L. A. et aI., AMER. JOURN. OF MED. ELEC- TRONICS, Jan-Mar, 1962, pp, 62-69 (copy in GR. 335, CL. 128/21) Kahn, A. et aI., AMER. JOURN. OF MED. ELEC- TRONICS, Apr.-.lune, 1963, pp. I52157 (copy in GR. 335, CL. 12812.1)

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Primary Examiner-Richard A. Gaudet Assistant Examiner-Kyle L. Howell Att0rneyMoIinare, Allegretti, Newitt. & Witcofi' ABSTRACT: The rate at which a human subject coughs may be determined by providing a microphone, a transmitter connected to the microphone, a receiver, a counter, and a conditioning circuit that enables the counter to advance in response to a cough sound.

PATENTEB JUL 20 IQTI INVLiN'IU/(S LEON/4RD C. GU/VN BY DONALD ABURNS 62 A TTORNEYS point, play back DIAGNOSTIC COUGH-MONITORING TECHNIQUES BACKGROUND OF THE INVENTION 1. Field of the Invention This invention basically relates to medical diagnostic methods, and is more particularly related to techniques for rnonitoringthe rate at which a human subject coughs.

. 2. Description of the Prior Art v The rate at which a patient coughs is of great interest to a physician who wishes to know thecondition of his patient, and i to a research scientist who wishes to test the effectiveness of medication adapted to alleviate coughing. Unfortunately, until the discovery of the present invention, determination of ppatients cough rate has depended on a variety of techniques requiring an inordinate expenditure of time or undue restriction of the patients mobility.

Of course, the rateat'which a patient coughsmay be determined by manual count of a thirdjparty, such as a nurse. How

ever, since thistechnique requires the continual presence of highly trained personnel, it is generally'too costly tube of practical value. Moreover, the technique is susceptible to a variety of human errors and is impossible to standardize, since some personnel .will count insignificant, low-volume coughs whereas others will ignore such sounds or fail to hear them at all.

The coughing sounds uttered by a'patieht may also be captured on a tape recorder. However, no saving of time or effort is thereby achieved, since trained personnel must, at some the. tape and count the number of coughs recorded. t s s H Certain mechanical devices designed to determine the rate at which a patient coughs have been devised, althougheach has exhibited deficiencies that-have limited'its usefulness. Such devices comprise a pneumaticband that is snugly fitted around the patients chest. This aspect of the device is a source of discomfort for the patient and raises the possibility limited extent.

SUMMARY OF THE INVENTION It has been surprisingly discovered that therate at which a patient coughs may be accurately determined by .using a I microphone, a transmitter, areceiver,aconditioningcircuit,

and a counter. In order to use the invention to best advantage,

themicrophone is placed adjacent a patients throat so that coughing sounds (as well as other sounds uttered by'the patient) are converted into corresponding electrical currents. The transmitter, which is preferably a small, miniature semiconductor type that can be held in the patients pocket, transmits waves corresponding to the currents. The waves are reconverted'to electrical signals -by the receiver in a wellknown manner. The signals produced by the receiver are con ditioned so that signals corresponding to coughingrsounds cause the counter to advance, whereas signals corresponding to other types of sounds ordinarily cause the counter to remain inactive.

Theadvantages achieved by the invention are at once apparent. Since the microphone 'maylbe extremely small and lightweight, it can be conveniently clipped to the collar of the .patient's shirt or even taped to his'throat without creatingany discomfort. The patient has little orflno incentive to. remove such a microphonmand the reliability of the device is thereby increased. Of course, no wires connect the transmitter to the receiver, so that the patients movement is in no way restricted. Thus, the patients coughing ratemay be continuously monitored, even when the patient leaves the room in which he is confined.

The invention has been thoroughly tested and is able to determine coughing rates with a surprising degree of accura- Cy. Moreover, the magnitude of the coughing sound to be monitored may be precisely ascertained and standardized by controlling the gain of the receiver and by properly adjusting the conditioning circuit. This feature is extremely important, since meaningful research cannot be conducted until the type of cough under investigation is defined and distinguished from other types of sounds.

DESCRIPTION OF THE DRAWING FIG. 3 is a schematic diagram of a preferred form of a conditioning circuit used in connection with the receiver shown in FIG. I.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring tothe drawing, a preferred form of the present invention basically comprises a microphone 6, a portable FM radiotransmitter 12', an FM radio'receiver 14, a conditioning circuit 36, and a counter 52.

More specifically, microphone 6 is a miniature type that converts sound waves into electrical'crurrents in a well-known manner. The microphone incorporates a clip 8 that may be affixed to a garment. Alternatively the microphone may be directly held to a patient by tape or an elastic band. In either case, the microphone is suff ciently small and lightweight so that the patient experiences no discomfort during its usage. Thus,.the patient has no incentive to remove the microphone. Microphone 6 is attached to transmitter 12 by a connector 10.

Transmitter I2 is a conventional battery-operated FM radio transmitter of a well-known type. As shown in FIG. 2, the transmitter is preferably small enough to fit inside the pocket of a garment worn by a patient whose coughing rate is to be monitored. Transmitter 12 is tuned to transmit radio waves in an unused portion of theFM radio band.

Receiver 14 comprises a conventional FM radio receiver that may be tuned to receive waves transmitted by transmitter 12. The transmitter waves are received via an antenna 16, and the receiver may be conveniently tuned by manipulating tuning dial 20 and simultaneously observing the needle of tuning meter 18. The gain of the receiver is controlled in a wellknown manner by manipulating gain dial 22. In accordance with conventional practice, receiver 14 also includes a loud speaker 24 that is connected through a. switch 26 to an output transfonner 28. As shown in FIG. 3, output transformer 28 comprises a primary coil 30 and a secondary coil 32.

Conditioning circuit 36 basically comprises a full-wave rectifier 38 that includes diodes 40-43 arranged as shown. The input terminals of the full-wave rectifier are connected through switch'26 to secondary coil 31. The output terminals of rectifier 38 are connected across a. resistor 46 that has a sliding contact 48 connected thereto. Contact 48 may be adjusted by manipulation of a threshold dial 49 (FIG. 1). Contact 48 is connected through a capacitor 50 to the gate 58 of a silicon-controlled rectifier 56 that is normally biased in its nonconductive state. The anode of the rectifier is connected .to a conventional electrical counter 52 that employs a digit roller dial 54 (FIG. 1). In order to operate the conditioning circuit and counter, 60 cycle, l volt electrical power is applied between terminals 60 and 62 from a source not shown.

The operation of the apparatus shown in the drawing, together with the preferred practice of the method aspect of the present invention, will now be described. in order to monitor the coughing rate of the patient shown in FIG. 2, microphone 6 is preferably attached adjacent the voice box of the patient by any convenient means, such as by bandage strips 7. Of course, any convenient method may be used to place the microphone adjacent the patients throat, such as an elastic band. Alternatively clip 8 may be attached to the collar of a garment worn by the patient. Transmitter 12 is preferably slipped into a pocket of the garment worn by the patient, or, when the patient is in bed, it may be placed on a bedstand.

In accordance with well-known principles, sounds uttered by the patient are converted by the microphone into corresponding electrical currents. These currents are carried through conductor 10 to transmitter 12 where they are used to modulate radiofrequency currents. The modulated currents are used to generate radio waves that are transmitted through the atmosphere. The transmitted waves are received at antenna 16 and are converted into corresponding electrical signals in a well-known manner. Since no wires connect the transmitter and receiver, the patient may leave his area of confinement without interfering with the cough-monitoring process, and sounds uttered by the patient will continue to be converted into waves that are received by receiver 14 even though the patient and receiver are separated by up to about 300 feet.

In order to tune receiver 14 to the frequency of the waves produced by transmitter 12, dial 20 is manipulated and tuning meter 18 is observed. In addition, switch 26 may be thrown to connect speaker 24 to transformer 28 so that sounds uttered by the patient are audible through the speaker. After the receiver is properly tuned, switch 26 is returned to the position shown in FIG. 3, so that the conditioning circuit is operated.

The electrical signals produced by receiver 14 in response to sounds uttered by the patient are conditioned as follows. The gain of receiver 14 is adjusted by manipulating dial 22 until coughing sounds exhibiting power less than a predetermined standard power do not activate counter 52. This feature is extremely important since it enables the type of coughing sounds being monitored to be standardized.

The electrical signals are further conditioned by the adjustment ofcontact 48 through the manipulation of dial 49. Applicants have discovered that by properly adjusting contact 48, electrical signals corresponding to a cough sound uttered by the patient advance counter 52, whereas signals corresponding to other types of sounds ordinarily cause the counter to remain inactive. Proper adjustment of contact 48 is readily 52. The electrical signals corresponding to cough sounds uttered by the patient trigger the rectifier into conduction, thereby advancing the counter 1 digit, whereas signals corresponding to other types of sounds do not trigger rectifier 56. As a result, the counter remains inactive and is not advanced.

Those skilled in the art will appreciate that the embodiments of the invention shown and described herein are merely exemplary of the preferred practice thereof, and that various modifications in the structure, methods of operation, and details of the embodiments may be affected without departing from the spirit and scope of the invention.

What we claim is:

l. A process for determining the rate at which a human subject coughs by using a microphone, a transmitter connected to the microphone, a receiver tuned to receive waves from the transmitter, and a counter connected to the receiver, comprising the steps of:

locating the microphone adjacent the throat of the subject so that sounds uttered by the subject are converted into corresponding electrical currents;

transmitting waves corresponding to said electrical currents by means of the transmitter; converting the waves transmitted by the transmitter into corresponding electrical signals in said receiver; and

conditioning said electrical signals so that signals corresponding to a cough sound uttered by the subject cause the counter to advance, whereas signals corresponding to other types of sounds cause the counter to remain inactive.

2. A process, as claimed in claim 1, wherein the step of conditioning said electrical signals comprises the step of adjusting the gain of said receiver.

3. A process, as claimed in claim 2, wherein the step of conditioning said electrical signals further comprises the steps of:

full-wave rectifying said electrical signals; and

filtering a portion of said full-wave rectified electrical signals.

4. A process, as claimed in claim 1, wherein the microphone is located in contact with the throat of the subject.

5. A process, as claimed in claim I, wherein the transmitter is a radio transmitter and the receiver is a radio receiver. 

1. A process for determining the rate at which a human subject coughs by using a microphone, a transmitter connected to the microphone, a receiver tuned to receive waves from the transmitter, and a counter connected to the receiver, comprising the steps of: locating the microphone adjacent the throat of the subject so that sounds uttered by the subject are converted into corresponding electrical currents; transmitting waves corresponding to said electrical currents by means of the transmitter; converting the waves transmitted by the transmitter into corresponding electrical signals in said receiver; and conditioning said electrical signals so that signals corresponding to a cough sound uttered by the subject cause the counter to advance, whereas signals corresponding to other types of sounds cause the counter to remain inactive.
 2. A process, as claimed in claim 1, wherein the step of conditioning said electrical signals comprises the step of adjusting the gain of said receiver.
 3. A process, as claimed in claim 2, wherein the step of conditioning said electrical signals further comprises the steps of: full-wave rectifying said electrical signals; and filtering a portion of said full-wave rectified electrical signals.
 4. A process, as claimed in claim 1, wherein the microphone is located in contact with the throat of the subject.
 5. A process, as claimed in claim 1, wherein the transmitter is a radio transmitter and the receiver is a radio receiver. 